How does the color of light affect the rate of photosynthesis

Certain wavelengths of light supply the correct energy for photosynthesis to occur. Reddish and bluish light is absorbed best by chlorophyll, and promotes photosynthesis; green light is absorbed the least (which is why chlorophyll looks green to us), and slows photosynthesis down. So, it is best to use red or blue light when growing plants.